I have a ridge carbide set but it’s essentially the same as the Forrest. I remove the flange that offsets the regular blade from the arbor and the dado set goes directly against the saw arbor. Dado kit uses a set of shims and a smaller end flange. if you’re using the 3/4 set then no shims are necessary as there’s enough recess in the end flange to fit the rest of the arbor.?